1. Field of the Invention
The present invention relates to a process for producing N-long-chain acyl acidic amino acids and in particular to a process for producing N-long-chain acyl acidic amino acids by reacting an acidic amino acid, glutamic acid or aspartic acid, or its salt with a long-chain fatty acid chloride.
2. Description of the Background
It is known that inorganic salts such as sodium, potassium salts, and the like, as well as organic salts such as triethanolamine salt, and the like, of N-long-chain acyl acidic amino acids such as N-long-chain acyl glutamic acid or aspartic acid have surface activating action, sterilizing action, and the like, and are thus useful for various purposes such as detergents, dispersants (i.e., dispersing agents), emulsifying agents, anti-fungus agents (i.e., antibacterial agents) and the like.
A method of condensing glutamic acid with a long-chain fatty acid chloride in an aqueous solvent in the presence of an alkali is known as a method of synthesizing N-long-chain acyl acidic amino acids such as N-long-chain acyl glutamic acid (e.g., see Reference Example at the beginning of column 7 of Japanese Published Patent Application Kokai No. 35058/1973). However, this prior art method has the problem that the yield of the desired N-long-chain acyl glutamic acid is low relative to the long-chain fatty acid chloride.
An improvement in the method is capable of producing the desired N-long-chain acyl acidic acid efficiently with improvement in the reaction rate and reaction yield, and the reaction is completed in high yields in a short time. In this method a tertiary amine or quaternary ammonium salt is used as the catalyst (Japanese Published Patent Application Kokai No. 35058/1973 supra). However, in this method, a catalyst should be used and additional problems are encountered such as the requirement for more facilities and additional process steps.
In an alternative method for increasing yield, the reaction is conducted in a mixed solvent of water and an organic solvent such as acetone, methyl ethyl ketone, dioxane, tetrahydrofuran or the like, but the use of these and other such organic solvents presents problems which include the requirement of additional facilities, the influence of such solvents on the working environment and, particularly safety considerations which include meeting fire code regulations and the consequent necessity of investing in facilities to meet fire code regulations.
Therefore, in view of the necessity for improving the working environment which employs organic solvents, thereby demanding vigilence in the safe handling of the solvents and the necessity of providing facilities to prevent the adverse impact of the organic solvents on the environment, a need has continued to exist for a method of producing N-long-chain acyl acidic amino acids in an aqueous solvent system without the use of any organic solvents.